The present invention relates to nursing bottles. More particularly, it relates to nursing bottles having a function of indicating the inner temperature of the liquid contained therein.
It is necessary to feed milk kept at a proper temperature in suckling the baby using a nursing bottle. If the temperature of milk is too high, the baby can be burnt. On the other hand, if the temperature of milk is too low, the baby can suffer from a laxity of bowels. Among other things, milk prepared at improper temperature is likely to be rejected by the baby.
Generally, the artificial feeding of milk to the baby is carried out by pouring warmed water to a nursing bottle, then the dry milk is dissolved in it and the milk is cooled to a proper temperature, which is normally at about 36.degree. C. plus/minus 2.degree. C. (96.degree. F. plus/minus 3.6.degree. F.). In order to determine the proper temperature the sensuous method, such as touching the nursing bottle or dropping a small amount of milk to the hand, is normally used. However, such sensuous methods can be unreliable for various reasons, e.g. the surface temperature of the hand.
Varous porposals have been made so far for the nursing bottles that can detect temperature without relying on the sensuous methods. One proposal is to detect temperature by the change of color using, e.g. heat sensitive paints or thermolabels, as disclosed in Japanese Utility Model Application Kokai Nos. 55-19609, 60-106634, 55-45387, 61-173038 and 62-1627.
While detection of the temperature of the inner liquid can be achieved by putting a bar thermometer, such as analog alcohol bar thermometer, into the liquid, not only it is a cumbersome job to do but also it can be bad for the health. Similarly, provision of a thermometer inside the bottle should be avoided in view of sanitation.
Thus, attempts have been made to detect the inner temperature from the outside by laying a thermometer within the material of the bottle or by attaching a thermometer on the side of the bottle or, alternatively, by sticking a bimetal thermometer or a digital liquid crystal thermometer to the outside of the bottle, as disclosed in Japanese Utility Model Application Kokai Nos. 63-38529, 56-116044, 62-148235, 57-5235, 57-113142, 61-171974, 59-69738 and 60-184544.
The Japanese Utility Model Application Kokai No. 62-117537 discloses a nursing bottle that indicates the liquid temperature digitally. As shown in FIG. 7, the bottle 11 is equipped with a thermoconductive thin film 12 and a sealing cap 13. The cap 13 is connected with a holding cap 17 which is equipped with a bar thermosensor 14, thermal detector 15 and a thermometer 16. The thin film 12 is extended by the action of the bar thermosensor 14, and the temperature of the milk is detected by the thermosensor 14 though the thin film 12.
Further, the Japanese Utility Model Application Kokai No. 62-6831 discloses a nursing bottle shown in FIGS. 10 and 11. A signal processor 18 is provided at the bottom of a bottle 11 which is provided, at the bottom, a concentric circular thermoelectric element 19. A temperature indicator 20 and a buzzer 21 are provided at the upper part of the bottle 11, which are connected to the signal processor 18 with a wiring 22.
However, according to the prior art of detecting the liquid temperature from the outside either by laying an analog bar thermometer inside the material of the bottle, or by providing it on the outer surface of the bottle, defects may not be avoided such as difficulty in reading the scale of the thermometer, particularly when the feeding of milk is made at night.
A digital indication of the temperature is much favorable by being able to indicate the temperature every moment. Generally, however, it is difficult to detect the accurate temperature if a digital liquid crystal thermometer is equipped intimately on the outer surface of the bottle due to the low thermoconductivity of the bottle made of glass or plastic materials. Further, the indicated temperature and the actual inner temperature may generally be different due to radiation of heat by air on the outer surface of the bottle.
For instance, where temperature is detected with the thermosensor 14 through the thin film 12 according to the proposal of the Japanese Utility Model Application Kokai No. 62-117537, the inner liquid must touch the thin film 12 either by making the bottle 11 upside down or by swinging the bottle in order to detect the accurate temperature, as shown in FIG. 8. Even so, a difference of temperature may result if the bottle 11 is allowed to stand for a while after touching of the thin film 12 to the liquid. Moreover, the nursing bottle by this proposition necessitates inconvenience that, as shown in FIG. 9, the sealing cap 13 attached to the opening of the bottle 11 and the holding cap 17 equipped with the thermosensor 14 must be taken off, after detection of temperature, and that a nipple 23 and and a nipple cap 24 must be fitted to the opening of the bottle 11. Still further, the temporary storage of the sealing cap 13, the nipple 23 and the nipple cap 24 causes another problem of sanitation.
Aside from the problem of accurate detection of the inner temperature, the nursing bottle requires sterilization by boiling and this is also true with the nipple and the nipple cap that contact the baby. The proposal made by the Japanese Utility Model Application Kokai No. 62-6831 would cause difficulty in sterilizing it by boiling, since the temperature indicator 20, the buzzer 21, the signal processor 18 and the wiring 22 are united with the bottle 11.